import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class JdbcUtils {
    // 加载配置文件
    private static Properties props = null;
    private JdbcUtils(){}
    // 只在JdbcUtils类被加载时执行一次！
    static {
        // 给props进行初始化，即加载dbconfig.properties文件到props对象中
        try {
            InputStream in = JdbcUtils.class.getClassLoader()
                    .getResourceAsStream("dbconfig.properties");
            props = new Properties();
            props.load(in);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        // 加载驱动类
        try {
            Class.forName(props.getProperty("driverClassName"));
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }
    }

    // 获取连接!
    public static Connection getConnection() throws SQLException {
        // 得到Connection
        return DriverManager.getConnection(props.getProperty("url"),
                props.getProperty("username"), props.getProperty("password"));
    }


}
